The overall goal of this research is the control of obesity in man. There are four specific aims: 1) Improvements in the theory and practice of behavioral control of obesity. Efforts in this direction include a) study of the transfer of learning from one behavior therapy task to another; b) evaluation of the relative effectiveness of spousal support and monetary reward as reinforcers in weight control programs; c) exploration of behavioral control of massive obesity; d) efforts at conditioning of specific food aversions; and e) study of the relative efficacy of different schedules of reinforcement of monetary rewards upon weight loss. 2) Exploration of other methods of control of obesity. These methods include a) psychoanalysis: personality characteristics of obese persons and treatment outcome; b) pharmacotherapy of obese persons suffering from binge-eating; c) surgical treatment of obesity by jejuno-ileal by-pass. 3) Development of methods for the direct measurement of eating behavior: a) laboratory study of liquid diets; b) semi-naturalistic study of solid diets; and c) naturalistic observations in cafeterias and in the home.